Magmatic Differentiation in the Teide–Pico Viejo Succession: Isotope Analysis as a Key to Deciphering the Origin of Phonolite Magma

In Tenerife, lavas of the recent Teide–Pico Viejo central complex show a marked bimodality in composition from initially mafic lava (200–30 ka) to highly differentiated phonolite (30–0 ka). Groundmass Sr–Nd–Pb–O and feldspar 18O data demonstrate open system behaviour for the petrogenesis of Teide–Pi...

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Bibliographic Details
Main Authors: Wiesmaier, Sebastian, Troll, Valentin R., Carracedo, Juan Carlos, Ellam, Robert M., Bindeman, Ilya, Wolff, John A., Deegan, Frances M.
Other Authors: 27667923400, 6602449850, 55663151400, 7004124766, 6701722315, 7401804837, 36141545000
Format: Book Part
Language:English
Published: Springer 2013
Subjects:
250621 Vulcanología
Country Rock
Felsic Magma
Fractional Crystallisation
Mafic Magma
Nepheline Syenite
North Atlantic
Online Access:http://hdl.handle.net/10553/70315
https://doi.org/10.1007/978-3-642-25893-0_10
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Summary:In Tenerife, lavas of the recent Teide–Pico Viejo central complex show a marked bimodality in composition from initially mafic lava (200–30 ka) to highly differentiated phonolite (30–0 ka). Groundmass Sr–Nd–Pb–O and feldspar 18O data demonstrate open system behaviour for the petrogenesis of Teide–Pico Viejo felsic lavas, but contamination by ocean sediment can be excluded due to the low 206Pb/204Pb ratios of North Atlantic sediment. Isotope mixing hyperbolae require an assimilant of predominantly felsic composition for the Teide–Pico Viejo succession. Unsystematic and heterogeneous variation of 18O in fresh and unaltered feldspars across the Teide–Pico Viejo succession indicates magmatic addition of diverse 18O assimilants, best matched by nepheline syenites that occur as fresh and altered lithic blocks in voluminous pre-Teide ignimbrite deposits. Rare earth element modelling indicates that nepheline syenite needs to be melted in bulk to form a suitable end-member composition. Energy-Constrained Assimilation Fractional Crystallisation (EC-AFC) modelling reproduces the bulk of the succession, which implies that the petrogenesis of Teide–Pico Viejo lavas is governed by the coupled assimilation of nepheline syenite during fractional crystallisation. The most differentiated (and most radiogenic) lava computes to >97.8 % assimilant, likely represented by a nepheline syenite bulk melt that formed by underplating with juvenile mafic material. These recent research developments therefore recognise a wider variability of magmatic differentiation processes at Teide–Pico Viejo than previously considered. 190 173

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